Aerosol-forming substrate with nitrogen-containing nucleophilic compound

ABSTRACT

An aerosol-forming substrate is provided, including: a) one or both of cellulose and cellulose derivatives; b) an aerosol-former present in an amount of 20 weight percent to 58 percent on a dry weight basis based on a total amount of the aerosol-forming substrate; c) from 0 weight percent to 5 weight percent of tobacco on a dry weight basis based on the total amount of the aerosol-forming substrate; d) a nitrogen-containing nucleophilic compound; and e) a disaccharide. An aerosol-generating article including a substrate portion containing the aerosol-forming substrate is also provided. An aerosol-generating system is also provided.

The present invention relates to an aerosol-forming substrate, anaerosol-generating article including a substrate portion comprising theaerosol-forming substrate and a system comprising the aerosol formingarticle and an aerosol-generating device including a heating chamber forinserting the aerosol-generating article.

It is known to provide an aerosol-generating article including anaerosol-forming substrate which comprises aerosol-formers, such aspolyhydric alcohols and nicotine. The aerosol-generating article isinserted into the heating chamber of an aerosol-generating device and isheated to a temperature at which one or more components of theaerosol-forming substrate are volatilised without burning theaerosol-forming substrate. These non-liquid aerosol-generating articlesmay or may not comprise tobacco. It is known that aldehydes, inparticular unwanted formaldehyde can be formed when burning tobacco intraditional cigarettes. However, aldehydes also may be formed whenheating aerosol-generating articles without burning the aerosol-formingsubstrate. Therefore, there is a need for reducing the formation ofunwanted aldehydes in the aerosol produced by heating aerosol-formingsubstrates without burning.

According to an embodiment of the invention there is provided anaerosol-forming substrate comprising:

a) one or both of cellulose and cellulose derivatives,

b) an aerosol-former,

c) from 0 weight percent to 5 weight percent, preferably from 0 weightpercent to 3 weight percent, more preferred from 0 weight percent to 1weight percent, most preferred from 0 weight percent to 0.5 weightpercent of tobacco on a dry weight basis based on the total amount ofthe aerosol-forming substrate, and

d) a nitrogen-containing nucleophilic compound.

It was surprisingly found that aerosol-forming substrates not containingtobacco or that are substantially free of tobacco, but comprising one orboth of cellulose and cellulose derivatives may produce an aerosolhaving a high concentration of aldehydes, in particular formaldehyde.The aerosol-forming substrate may comprise from 0.1 weight percent to 3weight percent, from 0.2 weight percent to 2.5 weight percent, or from0.3 weight percent to 2 weight percent of tobacco. The concentration offormaldehyde in the aerosol formed from such an aerosol-formingsubstrate may be several times higher than the concentration offormaldehyde in the aerosol of aerosol generating articles containing ahigher amount of tobacco of more than 70 weight percent.

The nitrogen-containing nucleophilic compound may provide an aerosolreduced in the amount of aldehydes compared to an aerosol-formingsubstrate which does not contain the nitrogen-containing nucleophiliccompound. Further, the nitrogen-containing nucleophilic compound mayprovide an aerosol free of aldehydes. Without being bound by any theory,the nitrogen-containing nucleophilic compound may either react with thealdehyde in the aerosol or reduce or prohibit the formation of thealdehyde in the aerosol-forming substrate in situ. Thus, thenitrogen-containing nucleophilic compound may serve as an aldehydescavenger. Therefore, any aerosol resulting from the above-mentionedaerosol-forming substrate may comprise less aldehydes compared toaerosol-forming substrates of the same composition, but lacking thenitrogen-containing nucleophilic compound.

Without being bound by any theory, the nitrogen-containing nucleophiliccompound may via the nitrogen-atom react with aldehydes, in particularformaldehyde, present in the aerosol. The compound may be particularlynucleophilic owing to the lone electron pair of the nitrogen-atom.

The nitrogen-containing nucleophilic compound may comprise groups suchas *—NH₂, *—NH—*, *—CN, NH₄+, or *—C(═O)—NH—*, wherein the bond “*—”indicates a bond to further moieties of the nitrogen-containingnucleophilic compound. Without being bound by any theory, thesenitrogen-atom containing groups may particularly well react with anyaldehyde formed upon heating of the aerosol-forming substrate or withchemical precursors to these aldehydes.

According to another embodiment of the invention, thenitrogen-containing nucleophilic compound may be one or both of anorganic or inorganic compound. In particular, the nitrogen-containingnucleophilic compound may be selected from a group consisting of:

-   -   an organic compound with an amino or amide group, preferably an        amino group, nitrogen-containing saccharide and polysaccharide,        or a nitrogen-containing plastic,    -   and inorganic ammonium compound,    -   or a combination thereof.

According to a further embodiment of the invention thenitrogen-containing nucleophilic compound may be selected from at leastone of:

-   -   an amino acid being selected from a group consisting of lysine,        glycine, cysteine, arginine, or homocysteine or a combination        thereof,    -   a tripeptide, including glutathione,    -   urea or an urea derivative or a combination thereof,    -   nitrogen-containing saccharide and polysaccharide being selected        from a group consisting of: glucosamine, galactosamine, or        chitosan, or a combination thereof,    -   a nitrogen-containing plastic being selected from        polyethylene-imine, polystyrene-acrylonitrile or        polyacrylonitrile butadiene-styrene or a combination thereof.

These compounds may be particularly well suited to react with thealdehyde. Thus, these compounds may reduce the concentration of thealdehydes, in particular the formaldehyde in the aerosol formed fromthese aerosol-forming substrates.

Particularly preferred may be compounds such as lysine, urea, chitosan,polyethylene-imine and di-ammonium phosphate or a combination thereof.

The tripeptide including glutathione may preferably be glutathione.

The urea derivatives may be selected from derivatives, wherein some orall of the hydrogen atoms of the —NH₂ groups are replaced by either C₁-to C₁₂-alkyl groups, aryl groups, hydrogen-groups or alkyl-hydroxygroups. Concrete examples may be N-hydroxy urea, N-alkyl urea or N-arylurea or any combination thereof.

The aerosol-forming substrate may contain from 0.1 weight percent to 10weight percent, 0.2 weight percent to 9 weight percent preferably from0.5 weight percent to 8 weight percent, most preferred from 1 weightpercent to 5 weight percent, even more preferred from 1 weight percentto 4 weight percent, or 1.5 weight percent to 3 weight percent of thenitrogen-containing nucleophilic compound on a dry weight basis based onthe total amount of the aerosol-forming substrate. These weight percentranges may be particularly advantageous to reduce the amount of thealdehydes, in particular the formaldehyde in the aerosol formed.Particularly preferred also may be a weight percent-range of 2 weightpercent to 4 weight percent. Such a range may reduce or completelyeliminate the aldehyde in the aerosol formed.

The cellulose present in the aerosol-forming substrate of the presentinvention may serve as a filler. In particular the cellulose may serveas a matrix for the aerosol-former which may be present in theaerosol-forming substrate. The cellulose may include particles with sizeof less than 100 micrometers. The cellulose may be in powder-form.

Cellulose may also comprise cellulose fibers. The cellulose fibers mayhave at length of larger than 200 micrometers. The fiber lengths mayvary from 200 to 2000 micrometers. The fiber widths may vary from 14 to32 micrometers. The cellulose fibers may serve as an agent reinforcingthe aerosol-forming substrate.

The cellulose derivatives may be derivatives wherein at least partly orcompletely the —OH groups of the D-glucose units of cellulose have beenreplaced by groups other than —OH groups. In preferred embodiments thecellulose derivatives may be cellulose esters and cellulose ethers.

Typical cellulose esters may be cellulose acetate, cellulose propionateor cellulose sulfate. Typical cellulose ethers may be cellulose ethers,wherein some or all of the hydrogen atoms of the —OH groups have beenreplaced by alkyl-groups, or carboxy alkyl groups. Suitable examples ofthe group of cellulose ethers may be methyl cellulose, ethyl cellulose,hydroxy ethyl cellulose, hydroxy propyl cellulose, ethyl hydroxy ethylcellulose or carboxymethyl cellulose (CMC) or any combination thereof.Particularly preferred may be carboxymethyl cellulose. The cellulosederivatives may serve as binder in the aerosol-forming substrate.

The one or both of cellulose and cellulose derivatives may be present inan amount of 15 weight percent to 85 weight percent, preferably 20weight percent to 80 weight percent, more preferred 25 weight percent to70 weight percent on a dry weight basis based on the total amount of theaerosol-forming substrate. These weight percent-ranges may beparticularly suited for the one or both of cellulose and cellulosederivatives in order to serve as a binder or as a filler.

In particular, cellulose may be present in an amount of 30 weightpercent to 70 weight percent, preferably in an amount of 35 weightpercent to 65 weight percent, more preferred in an amount of 30 weightpercent to 58 weight percent, even more preferably in an amount of 40weight percent to 60 weight percent, most preferred in an amount of 40weight percent to 50 weight percent. In particular, an amount of 45weight percent to 58 weight percent of cellulose on a dry weight basisbased on the total amount of the aerosol-forming substrate may bepresent. These weight percent ranges are preferred for cellulose andenable cellulose to particularly well serve as a filler in theaerosol-forming substrate.

The cellulose derivatives may be present in an amount of 1 weightpercent to 15 weight percent, or 1.5 weight percent to 12 weightpercent, preferably in an amount of 2 weight percent to 10 weightpercent, more preferably in an amount of 2.5 to 8 weight percent, morepreferably in an amount of 3 to 5 weight percent on a dry weight basisbased on the total amount of the aerosol-forming substrate.

The cellulose fibers may be present in an amount of 0.5 weight percentto 10 weight percent, preferably an amount of 1 weight percent to 8weight percent, more preferably in an amount of 2 weight percent to 6weight percent, most preferred in an amount of 2.5 weight percent to 5.5weight percent on a dry weight basis based on the total amount of theaerosol-forming substrate. These weight percent-ranges enable the fibersto particularly well serve as the re-enforcing agent for theaerosol-forming substrate.

In a further embodiment of the invention, one, two or all of cellulosepowder, cellulose fibers and cellulose derivative may be present in theaerosol-forming substrate. For example, the aerosol-forming substratemay comprise a combination of cellulose powder and a cellulosederivative, such as carboxymethyl cellulose. Alternatively, theaerosol-forming substrate may comprise combination of cellulose powderand cellulose fibers. In another alternative, the aerosol-formingsubstrate may comprise combination of cellulose fibers cellulosederivatives. Furthermore, the aerosol-forming substrate may onlycomprise the cellulose powder. The aerosol-forming substrate may alsoonly comprise the cellulose fibers or the cellulose derivatives. Inparticular, cellulose powder, cellulose fibers and cellulosederivatives, such as carboxymethyl cellulose may be included in theaerosol-forming substrate. The presence of all three components mayparticularly well enable these components to serve as a reinforcingagent, as a filler and as a binder.

The aerosol-forming substrate may comprise at least one aerosol-former.An aerosol-former is any suitable known compound or mixture of compoundsthat, in use, facilitates formation of a dense and stable aerosol andthat is substantially resistant to thermal degradation at thetemperature of operation of the aerosol-generating system. Suitableaerosol-formers may include, but are not limited to: polyhydricalcohols, such as triethylene glycol, 1,3-butanediol and glycerine;esters of polyhydric alcohols, such as glycerol mono-, di- ortriacetate; and aliphatic esters of mono-, di- or polycarboxylic acids,such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Aerosolformers may be polyhydric alcohols or mixtures thereof, such astriethylene glycol, 1,3-butanediol and glycerine. The aerosol-former maybe propylene glycol. The aerosol former may include both glycerine andpropylene glycol. The aerosol former may only include glycerine.

The aerosol-former may be present in an amount of 20 weight percent to58 percent, preferably 25 weight percent to 45 weight percent, morepreferred 30 weight percent to 38 weight percent on a dry weight basisbased on the total amount of the aerosol-forming substrate. The term“dry weight basis” throughout the application refers to the weight ofthe aerosol-forming substrate calculated with the water removed viaKarl-Fischer titration, for example after being heated to a temperatureof 110 degrees Celsius at standard conditions for temperature andpressure and using potentiometry to determine the endpoint. The endpoint is detected by a bipotentiometric titration method. A second pairof Pt electrodes is immersed in the anode solution. The detector circuitmaintains a constant current between the two detector electrodes duringtitration. Prior to the equivalence point, the solution contains I⁻, butlittle I₂. At the equivalence point, excess I₂ appears and an abruptvoltage drop marks the endpoint. The amount of charge needed to generateI₂ and reach the endpoint can then be used to calculate the amount ofwater in the original sample. The aerosol-former content can be measuredby gas chromatography in combination with a flame ionization detector.

In some embodiments, the aerosol-forming substrate may further include adisaccharide. In a preferred embodiment, the aerosol-forming substratemay include a disaccharide. Without being bound by any theory, thedisaccharide may serve to facilitate the conduction of heat from anoutside heating element into the aerosol-forming substrate. Thus, thedisaccharide may assist in a reliable formation of the aerosol once theaerosol-forming substrate is heated in a heating chamber by any outsideheating element.

Furthermore, without being bound by any theory, the disaccharide mayserve to modify the release of the aerosol-former during the course ofdifferent puffs taken by a user. For example, the presence of thedisaccharide may enable the release of the aerosol-former, for exampleglycerine over a longer, extended period of time. In particular, it maybe possible for a user to even enjoy an aerosol generated from theaerosol-forming substrate after having taken more than 6, 7 or 8 puffs.Normally, the amount of aerosol generated during these later puffs isreduced in comparison to the 3^(rd) or 4^(th) puff of the user.

The disaccharide may be selected from sucrose, lactose or maltose or acombination thereof. In preferred embodiments, the disaccharide issucrose.

The disaccharide may be present in an amount of 0.1 weight percent to 15weight percent, preferably 0.5 weight percent to 12 weight percent, morepreferred 1 weight percent to 10 weight percent on a dry weight basisbased on the total amount of the aerosol-forming substrate. These weightpercent-ranges may enable the disaccharide to particularly well extendthe release of the aerosol-former during the puffs taken by a user.Furthermore, these weight percent-ranges may also be well suited toenable the conduction of heat into the aerosol-forming substrate.

In some embodiments, the aerosol-forming substrate furthermore mayfurther comprise nicotine. Nicotine may form an important part of theaerosol generated from the aerosol-forming substrate upon heating.

The aerosol-forming substrate may comprise nicotine in an amount of 0.1weight percent to 10 weight percent, preferably 0.5 weight percent to 8weight percent, more preferred 1 weight percent to 3 weight percent on adry weight basis based on the total amount of the aerosol formingsubstrate. The nicotine content of the “dry weight” can also be detectedby gas chromatography in combination with a flame ionization detector.

The aerosol-forming substrate may additionally comprise at least onecarboxylic acid, preferably C₃ to C₆ alkyl hydroxy carboxylic acid, analkyl keto carboxylic acid or an aryl carboxylic acid. This at least onecarboxylic acid may protonate any nicotine present in theaerosol-forming substrate. Concrete examples of the carboxylic acid maybe lactic acid, benzoic acid, citric acid, malic acid, tartaric acid,2-methyl butyric acid, levulinic acid or any combination thereof.Preferably, the nicotine is protonated with the acid in a solution toyield the nicotinate. The nicotinate may then be employed with the othercomponents, such as the cellulose or cellulose derivatives in order toproduce the aerosol-forming substrate. For example, nicotine may be usedas 10 weight percent solution in glycerine and 2 molar equivalents oflactic acid may be added into slurry of remaining ingredients and mixed.The one or more protonated nicotine salts may have a higher solubilityin water compared to the nicotine free base. Preferably the one or morenicotine salt may be selected from the list consisting of nicotinecitrate, nicotine pyruvate, nicotine bitartrate, nicotine pectates,nicotine alginates, and nicotine salicylate. Nicotine in these saltforms is more stable than liquid freebase nicotine typically used. Thus,aerosol-forming substrates comprising these one or more nicotine saltsmay have longer shelf lives than typical aerosol-forming substrates.

The at least one carboxylic acid may be present in an amount of 0.1weight percent to 10 weight percent, preferably 0.5 weight percent to 8weight percent, more preferred 1 weight percent to 3 weight percent on adry weight basis based on the total amount of the aerosol-formingsubstrate.

The aerosol-forming substrate may comprise non-tobacco volatile flavourcompounds. These non-tobacco volatile flavour compounds may form anaerosol together with the aerosol-former upon heating of theaerosol-forming substrate. For example, non-tobacco volatile flavourcompounds may comprise menthol. As used herein, the term ‘menthol’denotes the compound 2-isopropyl-5-methylcyclohexanol in any of itsisomeric forms. The non-tobacco volatile flavour compounds may provide aflavour selected from the group consisting of menthol, lemon, vanilla,orange, wintergreen, cherry, and cinnamon.

The amount of the non-tobacco volatile flavour compounds in theaerosol-forming substrate may be between 0.1 weight percent to 54 weightpercent, preferably between 0.5 weight percent to 30 weight percent on adry weight basis based on the total amount of the aerosol-formingsubstrate.

According to a further embodiment of the invention, the aerosol-formingsubstrate may comprise from 0.1 weight percent to 3 weight percent oftobacco, preferably from 0.1 weight percent to 2 weight percent oftobacco.

According to a further embodiment of the invention, the aerosol-formingsubstrate is substantially free, more preferred free of any tobacco. Inthis case, the aerosol may be formed by the aerosol-former and—ifpresent—by one or both of nicotine and the non-tobacco volatile flavourcompounds. Tobacco flavour compounds may not substantially or not at allcontribute to the formation of the aerosol, when the aerosol-formingsubstrate is heated.

The one or both of cellulose and cellulose derivatives also may bederived from cellulose sources other than tobacco. For example, trees ornon-tobacco plants may serve sources for cellulosic materials. The oneor both of cellulose and cellulose derivatives therefore may not bederived from tobacco.

The presence and also the absence of tobacco in the aerosol-formingsubstrate can be positively identified by DNA barcoding. Methods forperforming DNA barcoding based on the nuclear gene ITS2 (internaltranscribed spacer 2) of tobacco, the rbcL and matK system as well asthe plastid intergenic spacer trnH-psbA, are well known in the art andcan be used (Chen S, Yao H, Han J, Liu C, Song J, et al. (2010)Validation of the ITS2 Region as a Novel DNA Barcode for IdentifyingMedicinal Plant Species. PLoSONE 5(1): e8613; Hollingsworth P M, GrahamS W, Little D P (2011) Choosing and Using a Plant DNA Barcode. PLoS ONE6(5): e19254).

The substrate portion comprising the aerosol-forming substrate may beformed as a sheet, preferably a cast sheet. The sheets of aerosol-formermay be formed by a casting process of the type generally comprisingcasting a slurry comprising one or both of cellulose and cellulosederivatives, and—optionally—aerosol-former and the nitrogen-containingnucleophilic compound onto a conveyor belt or other support surface,drying the cast slurry to form a sheet of the aerosol-forming substrateand removing the sheet of aerosol-forming substrate from the supportsurface. For example, in certain embodiments sheets of theaerosol-forming substrate for use in the invention may be formed from aslurry comprising cellulose, cellulose fibers, carboxy methyl celluloseand optionally glycerine by a casting process. Additionally, the slurrymay comprise additional components selected from: nicotine, nicotinesalts, the disaccharide.

In one embodiment, a slurry including the at least one of cellulose andcellulose derivatives, the aerosol-former, the nitrogen-containingnucleophilic compound and—if present—the tobacco is formed. Theingredients in the slurry may have a concentration of between 15 weightpercent to 25 weight percent, preferably 20 weight percent on a dryweight basis. Casted sheets may be formed from the slurry. The castedsheets may be formed by drying. The target sheet thickness may bebetween 200 micrometers to 300 micrometers, preferably 250 micrometers.The sheet weight may be between 160 to 180 grams/square meter.

Alternatively, the casting process for forming the sheet of non-tobaccomaterial may only employ one or both of cellulose and the cellulosederivative. The cast sheet may subsequently serve as a cellulosicabsorbent substrate for absorbing one or both of the nicotine,preferably the nicotine salt and the aerosol-former onto the sheet.Additionally, one or both of the nitrogen-containing nucleophiliccompound and the disaccharide also may be absorbed on the absorbentsubstrate or may be present during the casting process.

The nicotine, preferably the nicotine salt and the aerosol-former may becombined with water as a liquid formulation. The liquid formulation mayfurther comprise any of the above-mentioned non-tobacco volatile flavourcompounds. Such a liquid formulation may then be absorbed by the sorbentsubstrate or coated onto the surface of the sorbent substrate.

The substrate portion comprising the aerosol-forming substrate may beformed as a rod. The substrate portion may be provided comprising agathered sheet of non-tobacco material formed by the above-mentionedcasting process including at least the one or both of cellulose andcellulose derivatives. The substrate portion may be circumscribed by awrapper. The sheet of non-tobacco material may be textured or crimpedand may comprise a sorbent substrate, a nicotine salt, and anaerosol-former. The gathered sheet of material non-tobacco preferablyextends along substantially the entire length of the substrate portionand across substantially the entire transverse cross-sectional area ofthe substrate portion. The sheet may further comprise water.

The aerosol-forming substrate may comprise up to 5 weight percent oftobacco on a dry weight basis based on the total amount of theaerosol-forming substrate. This tobacco may comprise cast leaf tobacco,reconstituted tobacco, tobacco paper, tobacco powder, blended tobacco,strips, sheets, shredded tobacco, or any other suitable form of tobacco.The tobacco may be produced of sheets of homogenised tobacco materialsby a reconstitution process. These include, but are not limited to:paper-making processes of the type described in, for example, U.S. Pat.No. 3,860,012 or casting or ‘cast leaf’ processes of the type describedin, for example, U.S. Pat. No. 5,724,998. For example, in certainembodiments homogenized sheets including tobacco material for use in theinvention may be formed from a slurry additionally comprisingparticulate tobacco in addition to the other components for the slurrymentioned above.

As used herein, the term ‘gathered’ may denote that the sheet ofaerosol-forming substrate is convoluted, folded, or otherwise compressedor constricted substantially transversely to the cylindrical axis of therod.

The term ‘sheet’ may denote a laminar element having a width and lengthsubstantially greater than the thickness thereof.

Another embodiment of the present invention is directed to anaerosol-generating article comprising a substrate portion containing anaerosol-forming substrate as described herein. Preferably, the substrateportion in the article may be in the form of a rod.

The aerosol-generating article may further comprise a connect portion.The connect portion preferably may have a tubular hollow core. Such atubular hollow core may be located downstream of the substrate portionand may abut the aerosol-forming substrate.

The connect portion may be formed from any suitable material orcombination of materials. For example, the connect portion may be formedfrom one or more materials selected from the group consisting of:cellulose acetate; cardboard; crimped paper, such as crimped heatresistant paper or crimped parchment paper; and polymeric materials,such as low-density polyethylene (LDPE). In a preferred embodiment, theconnect portion may be formed from cellulose acetate and preferably maybe a hollow cellulose acetate tube.

The connect portion preferably has an external diameter that isapproximately equal to the external diameter of the aerosol-generatingarticle.

The aerosol-generating article further may comprise a tipping paperarranged at least partly wrapped around the connect portion and thesubstrate portion to overlap the connect portion and the substrateportion. Such a tipping paper may increase the stability of anaerosol-generating article.

A further aspect of the invention is directed to an aerosol-generatingsystem comprising the aerosol-generating article as described herein andan aerosol-generating device. The aerosol-generating device may comprisea heating element and a heating chamber for receiving saidaerosol-generating article. The heating element may be configured toheat the aerosol-generating article to a temperature ranging from 220degrees Celsius to 400 degrees Celsius, preferably from 250 degreesCelsius to 290 degrees Celsius. At these temperatures an aerosol may begenerated from the aerosol-forming substrate included in theaerosol-generating article. This aerosol may be reduced in aldehydes dueto the presence of the nitrogen-containing nucleophilic compound.

The aerosol-generating device may heat, but not combust theaerosol-generating article. Such electrically heated heat-not-burnaerosol-generating systems heat the aerosol-generating article to atemperature sufficient to produce an aerosol from the substrate withoutcombusting the substrate.

As used herein, the terms ‘upstream’ and ‘downstream’ are used todescribe the relative positions of components, or portions ofcomponents, of the aerosol-generating device and the aerosol-generatingarticle in relation to the direction in which a user draws on theaerosol-generating article inserted into the heating chamber of theaerosol-generating device during use thereof.

The aerosol-generating article may comprise a mouth end through which inuse an aerosol exits the aerosol-generating system and is delivered to auser. The mouth end may also be referred to as the downstream end. Inuse, a user draws on the downstream or mouth end of theaerosol-generating system, in particular the aerosol-generating articlein order to inhale an aerosol generated by the aerosol-generatingsystem. The aerosol-generating system comprises an upstream end opposedto the downstream or mouth end.

In some aspects of the disclosure, the heating element may comprise anelectrically resistive material. Suitable electrically resistivematerials include but are not limited to: semiconductors such as dopedceramics, electrically “conductive” ceramics (such as, for example,molybdenum disilicide), carbon, graphite, metals, metal alloys andcomposite materials made of a ceramic material and a metallic material.Such composite materials may comprise doped or undoped ceramics.Examples of suitable doped ceramics include doped silicon carbides.Examples of suitable metals include titanium, zirconium, tantalumplatinum, gold and silver. Examples of suitable metal alloys includestainless steel, nickel-, cobalt-, chromium-,aluminium-titanium-zirconium-, hafnium-, niobium-, molybdenum-,tantalum-, tungsten-, tin-, gallium-, manganese-, gold- andiron-containing alloys, and super-alloys based on nickel, iron, cobalt,stainless steel, Timetal® and iron-manganese-aluminium based alloys. Incomposite materials, the electrically resistive material may optionallybe embedded in, encapsulated or coated with an insulating material orvice-versa, depending on the kinetics of energy transfer and theexternal physicochemical properties required.

In another embodiment, heated aerosol-generating articles may be usedcomprising a combustible heat source and an aerosol-generating substratedownstream of the combustible heat source. For example,aerosol-generating articles with aerosol-generating substrates in heatedaerosol-generating articles of the type disclosed in WO-A-2009/022232may be employed, which comprise a combustible carbon-based heat source,an aerosol-generating substrate downstream of the combustible heatsource, and a heat-conducting element around and in contact with a rearportion of the combustible carbon-based heat source and an adjacentfront portion of the aerosol-generating substrate. However, it will beappreciated that aerosol-generating articles as described herein mayalso be used in heated aerosol-generating articles comprisingcombustible heat sources having other constructions.

As described, in any of the aspects of the disclosure, the heatingelement may be part of the aerosol-generating device. Theaerosol-generating device may comprise an internal heating element or anexternal heating element, or both internal and external heatingelements, where “internal” and “external” refer to theaerosol-generating article. An internal heating element may take anysuitable form. For example, an internal heating element may take theform of a heating blade. Alternatively, the internal heater may take theform of a casing or substrate having different electro-conductiveportions, or an electrically resistive metallic tube. Alternatively, theinternal heating element may be one or more heating needles or rods thatrun through the center of the substrate portion of theaerosol-generating article. Other alternatives include a heating wire orfilament, for example a Ni—Cr (Nickel-Chromium), platinum, tungsten oralloy wire or a heating plate. Optionally, the internal heating elementmay be deposited in or on a rigid carrier material. In one suchembodiment, the electrically resistive heating element may be formedusing a metal having a defined relationship between temperature andresistivity. In such an exemplary device, the metal may be formed as atrack on a suitable insulating material, such as ceramic material, andthen sandwiched in another insulating material, such as a glass. Heatersformed in this manner may be used to both heat and monitor thetemperature of the heating elements during operation.

An external heating element may take any suitable form. For example, anexternal heating element may take the form of one or more flexibleheating foils on a dielectric substrate, such as polyimide. The flexibleheating foils can be shaped to conform to the perimeter of the heatingchamber for receiving the aerosol-generating article. Alternatively, anexternal heating element may take the form of a metallic grid or grids,a flexible printed circuit board, a molded interconnect device (MID),ceramic heater, flexible carbon fibre heater or may be formed using acoating technique, such as plasma vapour deposition, on a suitableshaped substrate. An external heating element may also be formed using ametal having a defined relationship between temperature and resistivity.In such an exemplary device, the metal may be formed as a track betweentwo layers of suitable insulating materials. An external heating elementformed in this manner may be used to both heat and monitor thetemperature of the external heating element during operation.

The internal or external heating element may comprise a heat sink, orheat reservoir comprising a material capable of absorbing and storingheat and subsequently releasing the heat over time to the substrateportion of the aerosol-generating article. The heat sink may be formedof any suitable material, such as a suitable metal or ceramic material.In one embodiment, the material has a high heat capacity (sensible heatstorage material), or is a material capable of absorbing andsubsequently releasing heat via a reversible process, such as a hightemperature phase change. Suitable sensible heat storage materialsinclude silica gel, alumina, carbon, glass mat, glass fibre, minerals, ametal or alloy such as aluminium, silver or lead, and a cellulosematerial such as paper. Other suitable materials which release heat viaa reversible phase change include paraffin, sodium acetate, naphthalene,wax, polyethylene oxide, a metal, metal salt, a mixture of eutecticsalts or an alloy. The heat sink or heat reservoir may be arranged suchthat it is directly in contact with the substrate portion of theaerosol-generating article and can transfer the stored heat directly tothe substrate. Alternatively, the heat stored in the heat sink or heatreservoir may be transferred to the substrate portion of theaerosol-generating article by means of a heat conductor, such as ametallic tube.

Alternatively, to an electrically resistive heating element, the heatingelement may be configured as an induction heating element. The inductionheating element may comprise an induction coil and a susceptor. Ingeneral, the susceptor is a material that is capable of absorbingelectromagnetic energy and converting it to heat. When located in analternating electromagnetic field, typically eddy currents are inducedand hysteresis losses occur in the susceptor causing heating of thesusceptor. Changing electromagnetic fields generated by one or severalinduction coils heat the susceptor, which then transfers the heat to theaerosol-generating article, such that an aerosol is formed. The heattransfer may be mainly by conduction of heat. Such a transfer of heat isbest, if the susceptor is in close thermal contact with theaerosol-generating article.

The susceptor may be formed from any material that can be inductivelyheated to a temperature sufficient to generate an aerosol from theaerosol-forming substrate. A preferred susceptor may comprise or consistof a ferromagnetic material, for example a ferromagnetic alloy, ferriticiron, or a ferromagnetic steel or stainless steel. A suitable susceptormay be, or comprise, aluminium. Preferred susceptors may be heated to atemperature in excess of 250 degrees Celsius.

Preferred susceptors are metal susceptors, for example stainless steel.However, susceptor materials may also comprise or be made of graphite,molybdenum, silicon carbide, aluminum, niobium, Inconel alloys(austenite nickel-chromium-based superalloys), metallized films,ceramics such as for example zirconia, transition metals such as forexample iron, cobalt, nickel, or metalloids components such as forexample boron, carbon, silicon, phosphorus, aluminium.

Preferably, the susceptor material is a metallic susceptor material. Thesusceptor may also be a multi-material susceptor and may comprise afirst susceptor material and a second susceptor material. In someembodiments, the first susceptor material may be disposed in intimatephysical contact with the second susceptor material. The secondsusceptor material preferably has a Curie temperature that is below theignition point of the aerosol-forming substrate. The first susceptormaterial is preferably used primarily to heat the susceptor when thesusceptor is placed in a fluctuating electromagnetic field. Any suitablematerial may be used. For example, the first susceptor material may bealuminium, or may be a ferrous material such as a stainless steel. Thesecond susceptor material is preferably used primarily to indicate whenthe susceptor has reached a specific temperature, that temperature beingthe Curie temperature of the second susceptor material. The Curietemperature of the second susceptor material can be used to regulate thetemperature of the entire susceptor during operation. Suitable materialsfor the second susceptor material may include nickel and certain nickelalloys.

By providing a susceptor having at least a first and a second susceptormaterial, the heating of the aerosol-forming substrate and thetemperature control of the heating may be separated. Preferably thesecond susceptor material is a magnetic material having a second Curietemperature that is substantially the same as a desired maximum heatingtemperature. That is, it is preferable that the second Curie temperatureis approximately the same as the temperature that the susceptor shouldbe heated to in order to generate an aerosol from the aerosol-formingsubstrate.

When an induction heating element is employed, the induction heatingelement may be configured as an internal heating element as describedherein or as an external heater as described herein. If the inductionheating element is configured as an internal heating element, thesusceptor element is preferably configured as a pin or blade forpenetrating the aerosol-generating article. If the induction heatingelement is configured as an external heating element, the susceptorelement is preferably configured as a cylindrical susceptor at leastpartly surrounding the heating chamber or forming the sidewall of theheating chamber.

The heating element may heat the substrate portion of theaerosol-generating article by means of conduction. The heating elementmay be at least partially in contact with the substrate, or the carrieron which the substrate is deposited. Alternatively, the heat from eitheran internal or external heating element may be conducted to thesubstrate by means of a heat conductive element.

During operation, the aerosol-generating article may be completelycontained within the aerosol-generating device. In that case, a user maypuff on a mouthpiece of the aerosol-generating device. Alternatively,during operation only the substrate portion of the aerosol-generatingarticle may be contained within the aerosol-generating device. In thatcase, the user may puff directly on the aerosol-generating article.

The aerosol-generating device may comprise electric circuitry. Theelectric circuitry may comprise a microprocessor, which may be aprogrammable microprocessor. The microprocessor may be part of acontroller. The electric circuitry may comprise further electroniccomponents. The electric circuitry may be configured to regulate asupply of power to the heating element. Power may be supplied to theheating element continuously following activation of theaerosol-generating device or may be supplied intermittently, such as ona puff-by-puff basis. The power may be supplied to the heating elementin the form of pulses of electrical current. The electric circuitry maybe configured to monitor the electrical resistance of the heatingelement, and preferably to control the supply of power to the heatingelement dependent on the electrical resistance of the heating element.

The aerosol-generating device may comprise a power supply, typically abattery, within a main body of the aerosol-generating device. In oneembodiment, the power supply is a Lithium-ion battery. Alternatively,the power supply may be a Nickel-metal hydride battery, a Nickel cadmiumbattery, or a Lithium based battery, for example a Lithium-Cobalt, aLithium-Iron-Phosphate, Lithium Titanate or a Lithium-Polymer battery.As an alternative, the power supply may be another form of chargestorage device such as a capacitor. The power supply may requirerecharging and may have a capacity that enables to store enough energyfor one or more usage experiences; for example, the power supply mayhave sufficient capacity to continuously generate aerosol for a periodof around six minutes or for a period of a multiple of six minutes. Inanother example, the power supply may have sufficient capacity toprovide a predetermined number of puffs or discrete activations of theheating element.

Another aspect of the present invention is directed to a method ofoperating the aerosol-generating system as described herein, comprisingthe method steps:

-   -   A) inserting said aerosol-generating article into the heating        chamber,    -   B) heating said aerosol-generating article via the heating        element, thereby generating an aerosol and in aldehydes, wherein        the aldehyde reacts with nitrogen-containing nucleophilic        compound, resulting in an aldehyde reduced aerosol.

During the heating of said aerosol-generating article an aerosol may beprovided which is substantially free or completely free of the aldehyde.

During heating of said aerosol-generating article, formaldehyde may beformed as an aldehyde, wherein the formaldehyde reacts with saidnitrogen-containing nucleophilic compound, resulting in a formaldehydereduced aerosol. Formaldehyde may be one primary aldehyde formed duringthe generation of an aerosol from the aerosol-forming substrates of thepresent invention.

An aerosol-generating article comprising an aerosol-forming substrateaccording to any embodiments of the present invention may preferablycomprise one or both of urea and lysine in the aerosol forming substrateas a nitrogen-containing nucleophilic compound.

A further aspect of the present invention is also directed to the use ofa nitrogen-containing nucleophilic compound for removing an aldehydefrom an aerosol formed by a heating of an aerosol-generating article asdescribed herein.

During the use of the nitrogen-containing nucleophilic compound theaerosol may be heated to a temperature between 220 degrees Celsius to400 degrees Celsius, preferably from 250 degrees Celsius to 290 degreesCelsius.

Features described in relation to one embodiment may equally be appliedto other embodiments of the invention.

The invention will be further described, by way of example only, withreference to the accompanying drawings in which:

FIG. 1 shows a column chart of the formaldehyde contents of differentaerosol-generating articles containing tobacco as well as non-tobaccoaerosol-forming substrates;

FIG. 2 depicts a column chart of the formaldehyde content of differentaerosol-generating articles including different concentrations of urea;

FIG. 3 shows a column chart of the formaldehyde content of differentaerosol-generating articles including tobacco or other non-tobaccoaerosol-forming substrate with sucrose and lysine;

FIG. 4 shows the release of the aerosol-former glycerine during thecourse of 12 puffs taken by a user depending on the amount of thedisaccharide sucrose in the aerosol-forming substrate;

FIG. 5 depicts a schematic of an aerosol-generating system comprising anaerosol-generating device and an aerosol-generating article.

FIG. 1 depicts a column chart wherein the amount of formaldehydedetected in an aerosol generated from various aerosol-generatingarticles having a heating element at a temperature of 350 degreesCelsius. The substrate portion containing the aerosol-forming substrateof the aerosol-generating article was heated by an internal blade. Ingeneral, formaldehyde in smoke can be detected by trapping the aerosolin a DNPH derivatization solution (2,4-dinitrophenylhydrazine) using asmoking machine. Pyridine is added to quench the derivatizationreaction, maximum 15 minutes after the end of the aerosol collection. Asolution containing an internal standard is added to the stabilizedaerosol extracts before being analyzed using ultra performance liquidchromatography with MS-MS detection with an ESI (Electrosprayionization) source in a negative mode. In this figure and also in theFIGS. 2 and 3 the vertical axis denotes the amount of formaldehydedetected in micrograms/aerosol generating article. The column denotedwith 10 shows that 3.7 micrograms formaldehyde were detected in theaerosol of an aerosol-generating article including 75 weight percent ofa tobacco blend, 18 weight percent of glycerine as aerosol-former withthe remainder being binder. In contrast to the tobacco containingaerosol-generating article, 15.4 micrograms of formaldehyde could bedetected in the aerosol of an aerosol generating article including 45weight percent cellulose, 30 weight percent inositol, 20 weight percentglycerine and the remainder being binder (column denoted with 12). Theinositol serves as a plasticizer. The data show that up to 4-times moreformaldehyde is released from non-tobacco-containing aerosol-formingsubstrates in comparison to substrates containing tobacco. The columnsdenoted with 14 and 16 show that no formaldehyde could be detected inthe aerosol of aerosol-generating articles including 45 weight percentcellulose, 26.25 weight percent inositol, 20 weight percent glycerineand either 3.75 weight percent urea (column denoted with 14) or 3.75weight percent lysine (column denoted with 16). Thus, both urea andlysine can act as nitrogen-containing nucleophilic compounds reactingwith formaldehyde, thereby eliminating formaldehyde from the aerosol.

FIG. 2 depicts a column chart of the formaldehyde detected in theaerosol generated from various aerosol-generating articles having aheating element at a temperature of 350 degrees Celsius. The columndenoted with 18 shows that 3.5 micrograms of formaldehyde could bedetected in the aerosol formed from an aerosol generating articleincluding 75 weight percent of a tobacco blend, 18 weight percentglycerine and the remainder being binder. 2.11 micrograms formaldehydewas found in the aerosol of an aerosol generating article containing 56weight percent cellulose, 5 weight percent carboxy methyl cellulose, 1weight percent urea, 3 weight percent cellulose fibers and 35 weightpercent glycerine (column denoted with 20). Thus, the amount offormaldehyde in the aerosol could be reduced by 39 percent whenincluding 1 weight percent urea as a formaldehyde-scavenger. Noformaldehyde could be detected in the aerosol of the aerosol generatingarticle containing 49 weight percent cellulose, 8 weight percent carboxymethyl cellulose, 5 weight percent urea, 3 weight percent cellulosefibers and 35 weight percent glycerine (column denoted with 22).

FIG. 3 shows a column chart of the formaldehyde detected in the aerosolof various aerosol generating articles with different compositions. 3.31micrograms formaldehyde could be detected in an aerosol generatingarticle at 350 degrees Celsius of the heating element including 75weight percent of a tobacco blend including the other components asmentioned above for FIG. 2 (column denoted with 24). An aerosolgenerating article containing 58 weight percent cellulose, 35 weightpercent glycerine, 4 weight percent carboxy methyl cellulose and 3weight percent cellulose fibers generates 1.68 micrograms formaldehyde(column denoted with 26). In contrast to that, more formaldehyde, 2.61micrograms is detected in the aerosol of an aerosol generating articlein which 10 weight percent cellulose have been replaced by 10 weightpercent sucrose (column denoted with 28). This suggests that thepresence of the disaccharide, sucrose, increases the amount offormaldehyde. The release of formaldehyde associated with thedisaccharide can reliably be reduced or suppressed by including thenitrogen-containing nucleophilic compounds of the present invention inthe aerosol-forming substrates. The column denoted with 30 shows, thatno formaldehyde could be detected in the aerosol of an aerosolgenerating article including 56 weight percent cellulose, 35 weightpercent glycerin, 2 weight percent lysine as a nitrogen-containingnucleophilic compound, 4 weight percent carboxy methyl cellulose and 3weight percent cellulose fibers.

Similar results, which are not shown in the Figures were achieved, whenaerosol-generating articles with an aerosol forming substrate weighing0.5 grams and comprising 42 weight percent cellulose, 28 weight percentsorbitol, 20 weight percent glycerin, and either 5 weight percent theammonium phosphate, 5 weight percent chitosane, 5 weight percent lysine,5 weight percent urea or 5 weight percent polyethylene imine with theremainder being cellulose fibers and guar gum were heated to 350 degreesCelsius for 6 minutes. In all these cases no formaldehyde could bedetected with TG-GC-MS analysis.

FIG. 4 shows a graph, wherein the vertical axis depicts the amount ofglycerin per puff (micrograms/puff) detected by FT-IR and the horizontalaxis denotes the number of puffs. The graph depicts the amount ofglycerol detected in the aerosol during the course of 12 consecutivepuffs at a temperature of 250 degrees Celsius of the heating element.The graph denoted with 32 shows the amount of glycerine released from atobacco containing aerosol generating article with 75 weight percenttobacco, 18 weight percent glycerine and the remainder being binder forcomparison. The graph denoted with 34 shows the release of glycerinefrom an aerosol generating article containing 58 weight percentcellulose, 35 weight percent glycerine, 4 weight percent carboxy methylcellulose, and 3 weight percent cellulose fibers. The further graphsshow the release of glycerine from aerosol generating articles, whereineither 10 weight percent cellulose has been replaced by 10 weightpercent sucrose (graph denoted with 36) or wherein 20 weight percentcellulose has been replaced by 20 weight percent sucrose (graph denotedwith 38). It can clearly be seen that the addition of sucrose results ina delay of the release of glycerine, so that more glycerine is releasedat a later stage beginning with puff number 7 or 8.

FIG. 5 depicts a schematic of an aerosol-generating system comprising anaerosol-generating device 46 and an aerosol-generating article 40. Theaerosol-generating article 40 includes a substrate portion 42 and aconnect portion 44. The substrate portion 42 includes theaerosol-forming substrate of the present invention and is locatedupstream in the direction of the aerosol-generating article. Thedownstream connect portion 44 may comprise a tubular hollow portion,such as a hollow acetate tube. The aerosol-generating article 40 can beinserted into the heating chamber 48 of the aerosol-generating device 46in such a way, that the substrate portion 42 is neighbouring the heatingelement 50 of the heating chamber. Additional elements are present inthe aerosol-generating device 46, for example circuitry 52, such as amicroprocessor and a power supply 54, for example a battery. The powersupply and the circuitry as well as the heating elements can beelectrically connected via electrical connections 56. During use of theaerosol-generating device user may draw on the downstream end of theaerosol-generating article 40, which might be the connect portion 44 oran additional mouthpiece or filter, not shown in FIG. 5 for inhaling theaerosol formed during the heating of the substrate portion 42. Theaerosol may comprise a reduced concentration of aldehyde due to thepresence of the nitrogen-containing nucleophilic compound in theaerosol-forming substrate of the substrate portion 42.

1.-15. (canceled)
 16. An aerosol-forming substrate, comprising: a) oneor both of cellulose and cellulose derivatives; b) an aerosol-formerpresent in an amount of 20 weight percent to 58 percent on a dry weightbasis based on a total amount of the aerosol-forming substrate; c) from0 weight percent to 5 weight percent of tobacco on a dry weight basisbased on the total amount of the aerosol-forming substrate; d) anitrogen-containing nucleophilic compound; and e) a disaccharide. 17.The aerosol-forming substrate according to claim 16, wherein the weightpercent of the tobacco is from 0 weight percent to 0.5 weight percent.18. The aerosol-forming substrate according to claim 16, wherein thenitrogen-containing nucleophilic compound is one or both of an organicand inorganic compound, selected from a group consisting of: an organiccompound with an amino or amide group, a nitrogen-containing saccharideand polysaccharide, or a nitrogen-containing plastic, an inorganicammonium compound, or combinations thereof.
 19. The aerosol-formingsubstrate according to claim 16, wherein the nitrogen-containingnucleophilic compound is selected from at least one of: an amino acidbeing selected from a group consisting of: lysine, glycine, cysteine,arginine, homocysteine, or a combination thereof, a tripeptide,including glutathione, urea or a urea derivative or a combinationthereof, a nitrogen-containing saccharide and polysaccharide selectedfrom a group consisting of: glucosamine, galactosamine, chitosan, or acombination thereof, an inorganic ammonium compound selected fromammonium phosphate and ammonium metal phosphates, and anitrogen-containing plastic selected from polyethylene-imine, polystyrene-acrylonitrile, polyacrylonitrilebutadiene-styrene, or acombination thereof.
 20. The aerosol-forming substrate according toclaim 16, further comprising a disaccharide selected from sucrose,lactose, maltose, or a combination thereof.
 21. The aerosol-formingsubstrate according to claim 16, wherein the aerosol-forming substrateis substantially free of tobacco.
 22. The aerosol-forming substrateaccording to claim 16, wherein the one or both of cellulose andcellulose derivatives is selected from cellulose, cellulose ester orcellulose ethers, or a combination thereof.
 23. The aerosol-formingsubstrate according to claim 22, wherein the one or both of celluloseand cellulose derivatives is cellulose acetate orcarboxymethyl-cellulose.
 24. The aerosol-forming substrate according toclaim 16, wherein the aerosol-former is selected from polyhydricalcohols, esters of polyhydric alcohols, aliphatic esters of mono-, di-,or polycarboxylic acids, or a combination thereof.
 25. Theaerosol-forming substrate according to claim 16, further comprising: f)nicotine.
 26. The aerosol-forming substrate according to claim 16,wherein the aerosol-forming substrate is formed as a sheet.
 27. Theaerosol-forming substrate according to claim 16, wherein theaerosol-forming substrate is formed as a casted sheet.
 28. Theaerosol-forming substrate according to claim 16, wherein one or both ofcellulose and cellulose derivatives of component a) are present in anamount of 15 weight percent to 85 weight percent on a dry weight basisbased on the total amount of the aerosol-forming substrate.
 29. Theaerosol-forming substrate according to claim 16, wherein one or both ofcellulose and cellulose derivatives of component a) are present in anamount of 25 weight percent to 70 weight percent on a dry weight basisbased on the total amount of the aerosol-forming substrate.
 30. Theaerosol-forming substrate according to claim 16, wherein theaerosol-former is present in an amount of 25 weight percent to 45 weightpercent on a dry weight basis based on the total amount of theaerosol-forming substrate.
 31. The aerosol-forming substrate accordingto claim 16, containing from 0.2 weight percent to 5 weight percent ofthe nitrogen-containing nucleophilic compound on a dry weight basisbased on the total amount of the aerosol-forming substrate.
 32. Anaerosol-generating article, comprising: a substrate portion containingan aerosol-forming substrate according to claim 16, wherein thesubstrate portion in the aerosol-generating article is in a form of arod.
 33. An aerosol-generating system, comprising: an aerosol-generatingarticle comprising a substrate portion containing an aerosol-formingsubstrate according to claim 16, wherein the substrate portion in theaerosol-generating article is in a form of a rod; and anaerosol-generating device comprising a heating element and a heatingchamber configured to receive the aerosol-generating article, theheating element being configured to heat the aerosol-generating articleto a temperature ranging from 220 degrees Celsius to 400 degreesCelsius.
 34. The aerosol-generating system according to claim 33,wherein the heating element is further configured to heat theaerosol-generating article to a temperature ranging from 250 degreesCelsius to 290 degrees Celsius.
 35. A method of operating anaerosol-generating system according to claim 33, the method comprisingthe following steps: inserting the aerosol-generating article into theheating chamber; and heating the aerosol-generating article via theheating element, thereby generating an aerosol and an aldehyde, whereinthe aldehyde reacts with the nitrogen-containing nucleophilic compound,resulting in an aldehyde reduced aerosol.